Carpet and upholstery cleaning with fluid pumping safety feature

ABSTRACT

There is disclosed apparatus for cleaning carpets, upholstery and the like utilizing a motor driven separate reservoir system for supplying a cleaning solution to a remote cleaning head adapted to apply the cleaning solution to the material being cleaned, and a separate motor driven vacuum pick-up system for storing cleaning solution and entrained dirt picked up via the cleaning head. The vacuum system may typically include a vacuum tank and a vacuum pump driven by an electric motor for evacuating the vacuum tank. The reservor system includes in combination with a reservoir tank a cleaning fluid pumping circuit comprising fluid heating means, a fluid pump for supplying fluid from the reservoir tank to the heating means, pressure sensitive valve means for returning heated cleaning fluid to the reservoir tank when the fluid circuit to the cleaning head is closed, and flow sensitive means disposed between the reservoir tank and the fluid pump effective to disconnect the pump drive motor and shut down the fluid pump and heater when the supply of cleaning fluid in the reservoir tank is exhausted.

United States Patent [1 1 Colt Nov. 27, 1973 CARPET AND UPHOLSTERY CLEANING WITH FLUID PUMPING SAFETY FEATURE [75] Inventor: JamesG.C0lt,Bellm0nt,Mass.

[73] Assignee: Carpetceh C0rp., Everett, Middlesex County, Mass.

[22] Filed: Jan. 31, 1972 21 Appl. No.: 221,999

[52] U.S.Cl. ..L 15/321 PrimaryExaminerHarvey C. Homsby Assistant Examiner-C. K. Moore Att0rney-Me1vin E. Frederick [5 7] ABSTRACT There is disclosed apparatus for cleaning carpets, up-

holstery and the like utilizing a motor driven separate reservoir system for supplying a cleaning solution to a remote cleaning head adapted to apply the cleaning solution to the material being cleaned, and a separate motor driven vacuum pick-up system for storing cleaning solution and entrained dirt picked up via the cleaning head. The vacuum system may typically include a vacuum tank and a vacuum pump driven by an electric motor for evacuating the vacuum tank. The reservor system includes in combination with a reservoir tank a cleaning fluid pumping circuit comprising fluid heating means, a fluid pump for supplying fluid from the reservoir tank to the heating means, pressure sensitive valve means for returning heated cleaning fluid to the reservoir tank when the fluid circuit to the cleaning head is closed, and flow sensitive means disposed between the reservoir tank and the fluid pump effective to disconnect the pump drive motor and shut down the fluid pump and heater when the supply of cleaning fluid in the reservoir tank is exhausted.

5 Claims, 4 Drawing Figures HOT SOLUTION TO CLEANING HEAD 73 i To A.C. SOURCE Patented Ndv. 27, 1913 3,774,261

2 Sheets-Sheet 2 FIG.4

CARPET AND UPHOLSTERY CLEANING WITH FLUID PUMPING SAFETY FEATURE The present invention relates to carpet and upholstery cleaning apparatus, and more particularly to such apparatus for supplying a cleaning fluid to a cleaning head for application to a carpet and providing vacuum pick-up means to withdraw from the carpet the clean.- ing fluid and intrained dirt.

In the cleaning of carpet and upholstery, it has been found effective to discharge a jet of pressurized cleaning solution into the pile, nap, or weave of the fabric to be cleaned, and to thereafter apply suction to the fabric to withdraw the used cleaning solution from the fabric together with the dirt loosened and intrained in the cleaning solution.

Cleaning apparatus of the type referred to above may comprise, for example, a liquid tank and vacuum tank each mounted on separate base structures housing a drive motor and its associated components. A motor drives a suction blower, the intake side of which is coupled to the interior of the vacuum tank while the discharge side of the vacuum blower discharges to the atmosphere either directly or through a muffler. A liquid pump a] o driven by a motor is connected to draw liquid from the liquid tank and feed the liquid under pressure to heating means which is then discharged through a hose and control valve to a spray or cleaning head adapted to discharge the heated liquid onto the material being cleaned. For a more thorough discussion, reference is made to patent application Ser. No. 25,521, filed Apr. 3, 1970, now U. S. Pat. No. 3,663,984, and assigned to the same assignee as this application.

Other cleaning devices particularly devoted to commercial cleaning fields have been provided which include fluid distribution means and a vacuum means for picking up fluid andlloosened material from surfaces after the surface has been scrubbed by brushes or the like. Still other devices have been provided which include means for high pressure fluid distribution and vacuum pick-up means for receiving the fluid delivered to the surface to be cleaned. The picked-up fluid may or may not be returned for recirculation. These devices operate on the principle that the high pressure fluid delivery serves as the cleaning and scrubbing element thereby eliminating the use of brushes or other scrubbing devices.

Whether one is concerned with two-tank cleaning apparatus as described above or any other apparatus having similar power requirements, in every case the power consuming characteristic of the apparatus has in the past been effectively limited to relatively low levels. This power limitation is due to the fact that the National Electric Code requires that all residential and industrial conventional convenience outlets be wired and fused for only fifteen amperes.

In the past this limitation in available electrical power from any convenience outlet has severely limited the design, capability, and efficiency of such devices because their electrical power consumption must be limited to relatively low values, even if separate electrical devices are provided for connection to separate outlets as taught in the aforementioned patent application Ser. No. 25,521. For a description of a method of and apparatus for combining electrical power from two separately fused circuits and supplying same to carpet cleaning apparatus of the type here concerned, wherein current in excess of that available from one convenience outlet may be supplied to the vacuum drive motor for example, while still supplying sufficient current to the other power consuming devices, reference is made to patent application Ser. No. 154,889, filed June 21, 1971, US. Pat. No. 3,697,771, and assigned to the same assignee as this patent application.

It is an object of the invention to provide improved two-tank cleaning apparatus.

Another object of the invention is to provide an improved two-tank cleaning apparatus designed to deliver a heated cleaning solution under pressure to a surface to be cleaned and to recover the solution through the use of a vacuum system.

A further object of the invention is the provision of improved two-tank cleaning apparatus wherein cleaning fluid from a reservoir tank is at certain times returned to the reservoir tank under control of flow sensitive switching means.

A still further object of the invention is the provision of improved two-tank cleaning apparatus wherein cleaning fluid from a reservoir tank'is heated and at predetermined times returned via a fluid pump to the reservoir tank wherein flow sensitive means are effective to shut the pump down when the reservoir tank is empty or fluid does not continue to flow to the pump at the normal rate.

The novel features that are considered characteristic of the invention are set forth in the appended claims; the invention itself, however, both as to its organization and method of operation, together with additional objects and advantages thereof, will best be understood from the following description of a specific embodiment, when read in conjunction with the accompanying drawings, in which:

FIG. 1 is a diagrammatic view of a reservoir system in accordance with the invention;

FIG. 2 is a diagrammatic view of the vacuum pick-up system;

FIG. 3 is a side elevation partly in section and showing details of a flow sensitive switch shown in FIG. 1; and

FIG. 4 is a perspective view of a remote cleaning head for cleaning carpets together with a reservoir and vacuum pick-up system.

Directing attention now to the drawings, in FIG. 1 is shown the reservoir system designated generally by the numeral 10. The reservoir system may be supported by an acoustically insulated base housing as shown for example in FIG. 4, the reservoir or solution tank 12 being removably attached as by hooks or the like to the upper surface of the housing and the balance of the reservoir system more fully described hereinafter being contained in conventional manner within the base housing.

At the base of the reservoir tank may be provided two connections preferably of the conventional quick disconnect type so that the reservoir tank can be simply, quickly, and without loss of fluid, removed from the base housing while still containing a liquid or cleaning solution. Disposed within and supported by the base housing is an electric drive motor 15 coupled, for example, in conventional driving relationship via pulleys to a solution or liquid pump 16. While the electric drive motor must meet certain power requirements, the liquid pump employed may, in accordance with the invention, be of a simple and inexpensive type without any protective means or apparatus to protect the pump against damage in the event the pump inlet is not continuously supplied with fluid. Since several well-known types are suitable for the purpose, the details thereof are not illustrated or described herein.

The inlet or low-pressure side of the liquid pump 16 may be connected by a conventional pipe or liquid supply line 19, a pressure or flow sensitive switch 25 more fully disclosed hereinafter, and a flexible hose 26 to the quick disconnect connection 113 as shown.

As will become more evident hereinafter the inlet and outlet sides of the liquid pump need not be coupled through conventional by-pass means including pipes and a pressure regulator for maintianing a predetermined pressure at the outlet of the liquid pump as shown. The liquid pump may be of a conventional type as noted above and typically should at least be capable of providing an outlet pressure of about 100 psi at flow rates of about 2 gallons per minute. The outlet of the liquid pump 36 communicates through pipe 31 and a one-way check valve 32 with the lower end of a conventional electric type heater means 33 for at least maintaining the temperature of cleaning fluid at a suitable temperature to provide at the outlet of the heater, a temperature of, for example, about 160 F. The cleaning fluid is most conveniently initially provided in the tank 12 by mixing suitably hot water with concentrated detergents and the like. A suitable heater may be, for example, a Chromalox, Model No. B, manufactured by the Edwin L. Wiegand Company which includes adjustable thermostat means 33a to control the temperature to which the liquid is heated by the heater.

The outlet side of the heater 33 communicates through one port of a T-connection via pipe 34, flexible hose 3t), a pressure regulator 35, and connection 14 with the interior of the reservoir tank ll2. Through the other port of the T-connection, the outlet of the heater also communicates via pipe 36, filter 3'7, adjustable flow pressure valve 38, pressure gauge 39 and a quick disconnect connection ll with an insulated and flexible high temperature fluid hose 42, the remote end of which hose communicates with a suitable cleaning head more fully described hereinafter and in said application Ser. No. 25,521. Heated fluid may flow from the heater 33 in one of two directions, the first of which is through pressure regulator 35 and back into the reservoir tank and the second of which is via pipe 36, adjustable flow pressure valve 38 and flexbile hose 42 to the cleaning head. Pressure regulator 35 is adjusted to open and permit heated fluid to pass therethrough when the pressure in line 34 is greater than a predetermined amount such as, for example, 75 psi. Adjustable flow pressure valve 38 is a normally closed, solenoid actuated type flow valve having an on-off switch 46 connected in series therewith and a pilot light 37. Both the switch 46 and pilot light 47 are preferably mounted on the base housing. The pilot light 4'7 is of course lit when switch 46 is closed thereby indicating that valve 38 is in its actuated position.

When the control valve in the cleaning head is in its normally closed position, thereby preventing the discharge of cleaning fluid (or flexible hose 42 is disconnected thereby closing line 36 at connection 41), cleaning fluid in the reservoir tank will be continuously supplied to the heater 33, heated, and then circulated back into the reservoir tank 12. The adjustable flow pressure valve 38, pressure gauge 39, and one-half of connection 421 may be mounted in the base housing. The quick disconnect connection 41 is, of course,

poled such that the high temperature fluid line 36 is closed when the flexible hose 42 to the cleaning head is disconnected.

When the high temperature fluid line 36 is coupled to the cleaning head via hose 42 and the control valve at the cleaning head is opened, the heated fluid which previously was flowing back into the reservoir tank via pressure regulator now flows through the high temperature flexible hose 42 and is discharged at the cleaning head because the pressure on the heater outlet side of pressure regulator 35 drops below the critical pressure at which it is set and, accordingly, pressure regulator 35 closes. Upon closure of regulator 35, the heated fluid is directed to the cleaning head. When the control valve on the remote cleaning head is closed or hose 42 is disconnected, the pressure on the heater side of pressure regulator 35 increases thereby causing pressure regulator 35 to exceed its critical pressure and, hence, open and permit heated cleaning fluid to again be circulated back to the reservoir tank. As will now be obvious, there is a continuous flow of fluid from the reservoir tank to the heater and thence back to the reservoir tank except when fluid is permitted to be discharged at the cleaning head. This permits the solution in the tank to be at least continuously maintained at an initial predetermined temperature thereby allowing maximum cleaning capability to be effected by the cleaning solution.

The foregoing arrangement also results in continuous pressurized flow of fluid through the pump 16 irrespective of whether cleaning fluid is being used or not. Accordingly, during any time that motor 15 is actuated no damage can result to the motor driven pump or the system so long as sufficient cleaning fluid is contained in tank 12 to permit continuous circulation via pipes 26 and 30.

Directing attention now to FIG. 2 there is shown the vacuum tank pick-up system generally designated by the number comprising a vacuum tank 56 that may be removably supported as by hooks on a second base housing (not shown), a second drive motor 58, and a suction blower 59. The drive motor 58 may be drivingly connected as by a pulley-belt system to the suction blower 59. The suction blower may be of the positive displacement type. The specific type of suction blower employed is not material to the invention, and since several well-known types are suitable for the purpose, the details thereof are not illustrated or described herein. The outlet or high pressure side of the suction blower 59 communicates through a pipe 61 with one end of a silencer 62 which may be a muffler of the type used to muffle the exhaust noise of internal combustion engines and the like. The silencer 62 is preferably supported within the base housing as by support brackets or the like.

A suction type flexible hose is connected to the inlet or low pressure side of the suction blower 59 and extends upwardly through a hole in the base housing. The upper end of the flexible hose 60 is removably fitted onto the lower end of a suction tube 63 incorporated axially in the vacuum tank 56. The flexible hose 6th preferably is of the annularly corrugated, axially resiliently extensible type to pennit it to be easily connected and disconnected from the axial tube 63 of the vacuum tank 56.

A suitable base housing may be of sheet metal, cylindrical, mounted on casters, and of a size to receive the components as described hereinbefore.

The vacuum tank is of the same size and generally of the same structure as the reservoir tank. Each may comprise a conventional domed bottom, sealed into the lower end of a conical wall having a radially inwardly extending shoulder. While the upper end of the reservoir tank is open, that of the vacuum tank is closed, and has a suction relief valve 64 mounted thereon. The suction relief valve 64 is so adjusted that when the pressure within the vacuum tank drops below a pre-set minimum of the relief valve, the latter will open to permit atmospheric air to bleed in and thus limit the vacuum in the tank to the desired level. A conventional vacuum gauge 65 is mounted on the vacuum tank to indicate the degree of vacuum therein. Also mounted on the vacuum tank is a soiled water level control switch 66. Switch 66 is connected in series via conductor 67 with the drive motor 58 to shut the motor off when the liquid level in the vacuum tank approaches the top thereof. Also provided adjacent the top of the vacuum tank is a suction inlet 68 for communicating the vacuum hose 69 with the interior of the vacuum tank. The remote end of the vacuum hose 69 is coupled to the cleaning head as and for the purposes more fully described hereinafter. A drain valve 71 is also provided at a low point in the vacuum tank for draining soiled cleaning solution therefrom. An extension cord 72 is provided for connection to a suitable source of electric power for operating the motor 58. Similarly, an extension cord 73 may be provided for connecting drive motor of the reservoir system to a suitable but separately fused source of electric current. Pressure switch is connected in series with electric motor 15 via conductors 74. Flow sensitive switch 25 may be any conventional type such as, for example, a McDonnell No. FSl flow switch manufactured by McDonnell and Miller, Inc., of Chicago, Ill., which is comprised of an electrical switch portion controlled by a flow sensitive portion through which the monitored fluid flows. The point of actuation of the switch is variable whereby the switch can be set to be actuated from a minimum to a maximum flow velocity.

As shown in FIG. 2, the electrical switch portion of switch 25 is connected in series with the input line. Thus, when normal flow in hose 26 is interrupted, as when tank 12 is empty or flow via hose or line 36 is blocked, this condition is detected by switch 25 and the flow of current to motor 15, heater 33, and flow control valve 38 is interrupted. In short, the reservoir system is shut down, thereby presenting damage to heater 33 and/or damage to pump 16 that may otherwise result from their continued use without a continuous supply of fluid. It is to be understood that while switch 25 is shown as being located intermediate hoses 26 and l9 in the input line to pump 16, it can operatively be located in line 31 or line 34.

As shown in FIG. 3 a suitable flow switch 25 is comprised of a fluid' base portion 75 and a switch portion 76 separated by a movable diaphragm 77. The no load position of diaphragm 77 is adjustable toward and away from the switch portion via adjusting screw 78, movable flow sleeve 79 and spring 80 carried on pin 81 and abutting sleeve '79 and pin base member 82 centrally carried by the diaphragm. Fluid flowing from line 26 to line 19 flows through and fills the space under the diaphragm. An iron washer is centrally attached to the upper surface of the diaphragm, which in cooperation with the movable magnet 83 effects actuation of switch 84. Switch 84 is connected in series with one conductor of line 73 as shown in FIG. 1.

As may now be apparent, when adjusting screw 78 is set such that when fluid is flowing through base portion 75, magnet 83 is actuated to its flow position to maintain switch 84 in its closed position, thereby coupling motor 15 and the like to the source of current. However, when flow through line 26 :is blocked, or more likely, tank 12 is empty, diaphragm 77 and hence iron washer 85 moves away from magnet 83 until magnet 83 is actuated to its no flow position, thereby opening the circuit to motor 15.

While a particular flow switch has been shown and described, it is to be understood that the invention is not so limited and that other suitable fluid actuated switching means may be used, it only being necessary that when flow to pump 16 decreases or changes sufficiently, current to the pump drive motor is interrupted.

Referring now to FIG. 4, a suitable cleaning head is indicated generally by the numeral 181 and includes a floor tool head assembly 182 and a handle assembly 183. The floor tool head assembly includes a pick-up nozzle unit 184 to which is secured a roller 187. When the roller 187 is in contact with the surface of the car pet or the like being cleaned, the nozzle unit 184 is in contact with the surface being cleaned.

The nozzle unit 184 is generally hollow having converging front and rear walls and side walls defining a suction chamber having an elongated narrow suction opening. In the working position shown in FIG. 4, the nozzle opening of the nozzle unit is maintained in contact with an upper surface of a carpet being cleaned. Cleaning fluid dispensing means (not shown) may be disposed intermediate nozzle unit 184 and roller 187. Such cleaning fluid dispensing means may conventionally include a plurality of adjustable jet outlet nozzles each providing a fan shaped spray and uniformly spaced from one another on a common axis. The nozzles are preferably canted slightly such that the edges of the fan shaped spray from the nozzles overlap but do not interfere one with another. This is effective in preventing what is commonly referred to as streak lines in a carpet.

The operation of the illustrative form of the invention is as follows:

With the reservoir tank and vacuum tank pick-up systems assembled and the cleaning head operau'vely connected, the drive motors are connected to a source of electric current. A supply of cleaning solution such as, for example, heated water with suitable cleaning and/or solvent material in solution therein, is poured into the open top of the reservoir tank 12, the amount and type of solution used being determined by the nature of the cleaning job to be performed. With the drain valve 71 of the vacuum tank 56 closed, and the suction relief valve 64 and the pressure regulator valves 29 and 35 set to the desired settings, the separate drive motors 15 and 58 and the heating element of the heating means 33 are energized. With the reservoir system drive motor 15 and the heater 33 operating, the liquid in the reservoir tank is almost continuously being heated and the suction blower 59 immediately reduces. the pressure within the vacuum pick-up tank 56 which causes a partial vacuum in the suction hose 69. The control valve on the remote cleaning head being open, the

size of the suction nozzle is preferably such as to limit the flow of atmospheric air therethrough to a rate below the capacity of the suction blower 59, so that were it not for the vacuum relief valve 64, the vacuum in the hose 69 would be greater than desirable. Accordingly, a suitable setting of the vacuum relief valve 64 is such as to maintain the vacuum in the tank 56 at a suitable level below ambient atmospheric pressure. With the system thus operating and after a few moments have been allowed to permit the heating of the liquid in the heater 33, the control valve at the cleaning head may be opened to permit the discharge of cleaning fluid via appropriate nozzles onto the surface to be cleaned. For a further discussion of an appropriate cleaning head reference is made to said application Ser. No. 25,521.

The suction nozzle of the cleaning head is drawn in successive strokes across the material to be cleaned while at the same time operating the control valve as required to direct fan-shaped streams of heated cleaning fluid from jet outlet nozzles in the cleaning fluid dispensing means onto the material being cleaned. The dirt from the material being cleaned together with the cleaning solution used, and atmospheric air drawn through such material, are all sucked into the cleaning fluid pick-up chamber of the nozzle, passes thence through the vacuum hose 69 and are discharged in the vacuum tank 56 through the suction inlet tube 68.

The soiled cleaning fluid is discharged through the vacuum inlet tube 68 into the vacuum tank 56 in conventional manner to prevent the flow of said cleaning fluid through the suction blower. At desired intervals, the collected cleaning fluid may be withdrawn from the vacuum tank 56 by opening the drain valve 71.

All during the time that the system is being used, cleaning fluid is continuously being supplied to pump 16 and either returned to tank 12 or supplied to the remote cleaning head. Thus the pump is not exposed to any danger of failure resulting from a lack of input fluid at any time so long as some fluid is present in tank 12. When the fluid in tank 12 is exhausted, this condition is immediately detected by switch 25 which is effective to immediately shut down the reservoir system thereby preventing any possible damage to the pump 16 or heater 33 in the event it is not protected by a thermal cut-out switch. As will now be evident the present invention not only permits the use of inexpensive and/or unprotected pumps in addition to permitting the elimination and consequent cost of thermal protective means for the heater, thereby achieving not only more efficient operation but a reduction in component and assembly cost.

For rugs of average or small pile height and/or lightly soiled rugs, switch 46 which may be conveniently mounted on the base housing, is actuated to its closed position, thereby providing actuation of valve 38 and pilot light 47. When valve 38 which is arranged and adapted to provide two rates of flow onto the surface being cleaned, (a low flow of about 1 gallon per minute and a high flow of about 2 gallons per minute), is in its normally open or unactuated position, cleaning fluid flows through it at the high flow rate.

When switch 46 is closed, valve 38 is actuated and permits cleaning fluid to flow therethrough at the low flow rate;

The provision of a low flow and a high flow rate is particularly advantageous when the remote cleaning head is of the small hand held type useful for cleaning carpets on stairs, in corners, and furniture and the like.

While a preferred embodiment of the invention has been illustrated and described, it will be understood, however, that various changes and modifications may be made in the details thereof without departing from the scope of the invention as set forth in the appended claims.

Having thus described the invention, what is claimed as new and desired to protect as Letters Patent is:

1. In a two tank cleaning apparatus for cleaning carpets and the like in situ comprising a cleaning solution reservoir tank system, a vacuum tank pick-up system, and a remote cleaning head; said reservoir tank system comprising a reservoir tank, electric heater means having an inlet and an outlet, a liquid pump having an inlet for receiving liquid from said reservoir tank and an outlet for supplying it under pressure to the inlet of said heater means, a first electric drive motor for actuating said liquid pump, conductor means for connecting said first motor to a source of electrical power, and first flexible hose means for receiving heated liquid from the outlet of said heater means and supplying it under pressure to said cleaning head; said vacuum tank pick-up system including a vacuum tank, second flexible hose means coupling the interior of said vacuum tank to said cleaning head, an air suctionblower having an outlet and an inlet, said inlet being coupled to said vacuum tank for evacuating air from said vacuum tank, and a second electric drive motor for actuating said suctionblower, the improvement comprising:

a. a first liquid supply line coupling said reservoir tank to said pump inlet, said first line (for) supplying liquid to said pump inlet only from said reservoir tank;

b. a second liquid supply line coupling the outlet of said pump to the inlet of said heater means ,said second line (for) supplying liquid only to said heater means;

0. a third liquid supply line coupling the outlet of said heater means to said reservoir tank;

d. a fourth liquid supply line having one end coupled to the outlet of said heater means for supplying heated fluid to said cleaning head;

e. pressure regulator means for permitting liquid to flow from said heater and back to said reservoir tank through said third liquid supply line when flow through said fourth line is prevented, said first, second and third liquid supply lines, pump, heater, and pressure regulator means comprising a liquid pumping circuit whereby liquid may flow from said reservoir tank, through said liquid pumping circuit and back to said reservoir tank when flow through said fourth line is blocked, liquid supplied to said pump inlet flowing thereto only from said reservoir tank and liquid from said pump outlet flowing only to said heater means; and

f. liquid flow operated switch means actuated by fluid flow in said liquid pumping circuit eflective to prevent the application of electrical power to said first drive motor when liquid flow in said liquid pumping circuit drops below a predetermined level.

2. The combination as defined in claim 1 wherein said liquid operated switch means is effective to prewhen liquid flow in said liquid pumping circuit drops below said predetermined level.

5. The combination as defined in claim 4 (6) wherein said liquid operated switch means is disposed between said reservoir tank and said pump, and additionally including means for adjusting said liquid flow actuating means to actuate said electrical switch at different liquid flow levels. 

1. In a two tank cleaning apparatus for cleaning carpets and the like in situ comprising a cleaning solution reservoir tank system, a vacuum tank pick-up system, and a remote cleaning head; said reservoir tank system comprising a reservoir tank, electric heater means having an inlet and an outlet, a liquid pump having an inlet for receiving liquid from said reservoir tank and an outlet for supplying it under pressure to the inlet of said heater means, a first electric drive motor for actuating said liquid pump, conductor means for connecting said first motor to a source of electrical power, and first flexible hose means for receiving heated liquid from the outlet of said heater means and supplying it under pressure to said cleaning head; said vacuum tank pick-up system including a vacuum tank, second flexible hose means coupling the interior of said vacuum tank to said cleaning head, an air suctionblower having an outlet and an inlet, said inlet being coupled to said vacuum tank for evacuating air from said vacuum tank, and a second electric drive motor for actuating said suction-blower, the improvement comprising: a. a first liquid supply line coupling said reservoir tank to said pump inlet, said first line (for) supplying liquid to said pump inlet only from said reservoir tank; b. a second liquid supply line coupling the outlet of said pump to the inlet of said heater means ,said second line (for) supplying liquid only to said heater means; c. a third liquid supply line coupling the outlet of said heater means to said reservoir tank; d. a fourth liquid supply line having one end coupled to the outlet of said heater means for suPplying heated fluid to said cleaning head; e. pressure regulator means for permitting liquid to flow from said heater and back to said reservoir tank through said third liquid supply line when flow through said fourth line is prevented, said first, second and third liquid supply lines, pump, heater, and pressure regulator means comprising a liquid pumping circuit whereby liquid may flow from said reservoir tank, through said liquid pumping circuit and back to said reservoir tank when flow through said fourth line is blocked, liquid supplied to said pump inlet flowing thereto only from said reservoir tank and liquid from said pump outlet flowing only to said heater means; and f. liquid flow operated switch means actuated by fluid flow in said liquid pumping circuit effective to prevent the application of electrical power to said first drive motor when liquid flow in said liquid pumping circuit drops below a predetermined level.
 2. The combination as defined in claim 1 wherein said liquid operated switch means is effective to prevent application of electrical power to said electric heater means.
 3. The combination as defined in claim 1 (3) wherein said liquid operated switch means is disposed between said reservoir tank and said pump.
 4. The combination as defined in claim 1 wherein said liquid operated switch means comprises an electrical switch having an open position and a closed position and liquid flow actuated means for actuating said electrical switch to its open and closed positions, said electrical switch being actuated to its open position when liquid flow in said liquid pumping circuit drops below said predetermined level.
 5. The combination as defined in claim 4 (6) wherein said liquid operated switch means is disposed between said reservoir tank and said pump, and additionally including means for adjusting said liquid flow actuating means to actuate said electrical switch at different liquid flow levels. 